EL + PE (Update)
Electroluminescent Lights + Piezo Electricity
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Solution

This concept makes flooring more useful, safe and interactive.
Electrical energy is generated from the mechanical pressure of footsteps during the day. This energy is stored and used to power EL (electroluminescent) lights at night to provide a safe walking path ahead of the walker(s).
This can also be used as a dancefloor that lights up at parties!
See http://powerleap.net/?page_id=32 for info about one attempt at generating energy from footsteps. The proposed construction is much less expensive, attractive, and effective for its intended purpose.

Warning!  Boring technical stuff follows...

Materials:
The substrate of these boards can be constructed of ANY non-conductive materials.  For example, locally grown Bamboo. Reiner Winkendick currently grows bamboo in the outskirts of Amsterdam. http://www.pflanzenhandelwinkendick.de/english/overview/
The construction details for these floor panels is shown in the second sketch. This is envisioned as an extruded profile that is then laminated with different layers in a continuous in-line process. Note that the laminated layers are easily held in place using pressure sensitive adhesive as the loading is consistently downward.
The top elastomeric layer provides some movement for the PE film along with a seal along the edges to keep moisture out..

After lamination,the boards (or square tiles) can be cut to just about any length and still light, as the connections are made along the sides. 

Energy Production and Storage

 The voltage and power output from a single Piezoelectric (PE) film is very low... in the range of 1.0 Volts and 0.2 mW, respectively, while electroluminescent (EL) materials requires 50 to 120 volts and 700mW of high frequency power to light them up. This implies that a voltage converter and inverter needs to be employed to provide the required output current profile. Note that solid state voltage converters/inverters are already on the market and are easily fit onto a small circuit board in the control panel.

However, the difference in input PE and output EL power implies that direct application of one piezo-film as a power source for a tile is not really practical. Therefore, a storage device, such as a a small metal hydride battery will be used to collect the weak, generated electrical power during the day for reuse after it gets dark. This one, central battery pack would store the footfall energy from the entire house and direct it where and when it is needed 
In this way, small PE inputs can light your floor at night.

How does your idea solve the problem?

The floorboards light a path to various rooms in the house. The system will involve light sensors to detect light levels and pressure sensors to detect that someone has just stepped onto the floor.

Which materials are you using and why?

Bamboo since it reaches maturity every 3-5 years (as opposed to 20-120 years for hardwoods). It is also currently being grown in Germany. EL lights in the floorboard. Piezoelectric plates underneath

Which aesthetic does your idea follow?

To be decided, by you... The top laminate is printed in any way you wish.

What is the benefit of your idea for the target group?

Allows the user to use energy they have exerted during the day to provide light at night. Prevents the user from having to use room lights or lamps. Saves energy and could prevent waking up others.

Which problem does your idea solve?

Accidents caused while having to move around the house at night. (Ie. picking up the phone, going to the toilet, responding to noises/fires/intruders). It has a secondary usage as a dancefloor.